A hook shot in basketball is a shot attempt where a player swings his or her arm sideways in a hooking motion with the ball usually over the side of his or her head. The hook shot is generally only performed within close range of the hoop, since it can be more difficult to aim than a regular shot. It is also more often performed by taller players, since it can be difficult for defenders to block with the offensive player's body turned sideways.
Also known as the "baby hook," the jump hook typically begins with the offensive player obtaining the ball close to the basket, with their back facing toward it. The player then pivots so that their shoulder is now facing the basket and they jump from both feet, lifting the ball above their head and flicking their wrist to put it into the basket. It is called the "jump" hook since it resembles a jump shot, with the jump and the wrist flick.
The modern sky hook was popularized by NBA legend Kareem Abdul-Jabar in the 1980's. A player with receive the ball near the basket, pivot on the foot that is on their non-shooting hand side, and turn so that their shoulder faces the basket. The player will then jump from one foot and hook their arm over their head so that the ball goes into the hoop. This is a more traditional looking hook shot, but is still very effective for taller players to shoot over smaller defenders.